Socioeconomic status (SES) during early life is an important determinant of vulnerability to cardiovascular disease in adulthood. Because these effects are not simply a result of the more direct influences of social standing in adulthood, they raise challenging mechanistic questions about how early-life SES gets biologically embedded for the long-term. This proposal advances an epigenetic programming hypothesis to explain this process. It posits that psychosocial experiences associated with low early-life SES are programmed in the genome via epigenetic mechanisms, or acquired changes in genomic activity that are not due to changes in DNA sequence. In a study of 420 volunteers, we will evaluate the hypothesis that individuals who spent their early years in low-SES environments were exposed to greater familial turmoil and have developed vigilant, pessimistic outlooks on life. We further expect these experiences to have become embedded in the immune system through epigenetic modifications, and to manifest as a pro-inflammatory phenotype beginning in adolescence and persisting through adulthood. This phenotype will be characterized by activation of pro-inflammatory transcription control pathways and increased concentrations of the inflammatory biomarkers C-reactive protein and interleukin-6. This work will shed light on the biobehavioral mechanisms underlying SES disparities, with implications for preventative interventions.